1. Field of the Invention
This invention relates to methods for making relative pressure measurements by means of manometer-like devices. More specifically, the invention relates to methods for measuring the density of a vapor, changes in a liquid level, the average specific gravity of a liquid, changes in the amount of solids or liquids entrained in a vapor, and the interface between two immiscible liquids by means of manometer-like devices.
2. Prior Art
Methods for measuring relative vapor pressures, by means of manometer-like devices are well known. "Manometer-like" devices means throughout this specification and the claims a relative pressure measuring device wherein a first pressure is measured relative to a second pressure by balancing the difference in pressure between said first and second pressure by a fluid-head. A "fluid-head" means, throughout this specification and claims, the product of the difference in relative heights between a first fluid level, e.g., a first liquid and a second fluid level, e.g., a second liquid, times the density of said first and said second fluid, when said first and said second fluids are of the same density. More generally, a fluid-head, where two immiscible fluids, e.g., liquids, make up the "fluid-head" requires a balancing of the contributions made by each of the fluids, as is clear to one of skill in the art.
To determine vapor density by means of relative pressure measurements can involve very small changes in relative liquid levels. For example, changes in relative liquid levels can be less than one-thousandth of an inch. Similarly, to locate a a liquid interface by means of manometer-like devices may be very difficult since the changes in relative liquid levels can be very small, e.g., less than a thousandth of an inch.